In this article, Ciaran Hamill, CAFRE senior beef and sheep adviser, Armagh, looks at factors that impact the level of return from reseeding ground.
It takes effort and expense to plan and manage an autumn reseed, but the return on that investment can be significant.
Reseeding will improve pasture quality, helping drive increased output.
It will allow the use of newer, more nitrogen-efficient grass varieties, making the best use of any applied nitrogen (N), and allow for the introduction of clover, again helping to reduce overall N use.
Before deciding to reseed, you need to do some work. There are several points to consider.
An autumn reseed will generally have less impact on the overall annual production than a spring reseed, due mostly to the seasonal grass growth pattern.
What is the existing sward composition and performance? Have you measured grass production, and are you sure reseeding is the best option to improve grass growth?
Is the field you plan to reseed the one on your farm that really needs action taken?
When did you take the last soil sample in the field, and do you know the soil nutrient status?
If you are in Zone 1 of the Soil Nutrient Health Scheme, you should take the opportunity to apply for soil sampling of all fields on your farm as soon as possible.
It may be the case that addressing pH, P and K deficiencies and making better use of slurry and farmyard manure will improve performance.
Reseeding alone will not correct soil nutrient management issues.
Whether you reseed or not, addressing soil nutrient status issues will be a very good investment.
If you do plan to reseed, then a soil sample and correcting any pH, P or K deficiency is a must.
If there is a significant weed burden, e.g., docks or thistles, spraying to reduce the burden may be worthwhile before going to a full reseed.
This is especially true when looking at increasing clover content when post-emergence spraying of the new sward will be restricted.
- Have you examined the field soil structure? Are there any areas of compaction or areas where drainage may have been compromised? Reseeding is a chance to do some remedial work on compaction and drainage, but other interventions such as mole ploughing or sward lifting could be beneficial before reseeding.
- What is your current stocking rate? Do you have enough grass, and are you happy with animal performance? Reseeding will normally lead to an increase in grass production as the major return on investment. Can you utilise more grass effectively with your current stock and grazing system?
- Do you primarily use the field for grazing, silage or both? The recommended lists will show the best varieties of grass and clover to use in specific circumstances, and all the major seed merchants have an excellent range of mixes to suit each situation. The best advice is to ensure that the varieties in your mix are all as far up as possible on the recommended lists available.
In most cases, spraying the old sward to kill existing grasses and weeds is recommended.
Ideally, graze the sward tightly and allow a short time for recovery to give enough leaf for the spray to work, with the least amount of residual sward to decompose.
The most reliable yet the most expensive
A traditional plough/power harrow/roll/seed/roll operation is considered the most reliable and the most expensive.
It will address any surface compaction issues but will also be slightly longer before grazing can restart.
Minimal tillage or direct drilling are good options where soil conditions are favourable, and there is minimal existing sward to hinder seed-soil contact and seedling emergence.
Options when reseeding ground
When considering what varieties to sow, there are plenty of options.
The options include multispecies herbal mixes, ryegrass only mixes, the inclusion of species such as fescues, timothy and cocksfoot for heavier soil types and ryegrass/clover mixes.
Research by Teagasc on both dairy and sheep farms has shown that a grass + clover with significantly less N input can support a similar stocking rate and deliver a higher margin per hectare than a grass-only sward with higher N input.
Consider all the factors mentioned above, as well as your own ability to manage grazing when deciding what mix to use.
Introducing a paddock grazing system alone can increase grass production and utilisation.
If you go to the expense of reseeding, then a good grazing system is key to realising the most from this investment.
When is the best time to sow? Grass and clover seeds need soil contact, moisture and warmth to germinate and thrive.
What is the weather going to be like? Drought-stricken or waterlogged soils are both detrimental to plant survival.
After mid-September, frost can start to impact soil temperature, plant germination and survival. Sow as soon as possible.
Post-emergence management is very important. Consider weed control, and take care to use the right spray if clover has been used in the mix.
Light grazing, with young cattle or sheep, if possible, when seedlings have a good root structure developed, will help plant tillering and ground cover. Do not overgraze.
Forage crops may be a short-term option on dryer fields that you can graze over winter. Have you considered brassicas or another direct drilled forage for winter grazing, leading into an early spring reseed?
Deciding to reseed requires a lot of effort, but with the right planning and careful execution, it will be a productive and profitable investment.